The present invention relates generally to the interfacing with computer devices by a user, and more particularly to devices used to provide input to computer systems and which provide force feedback to the user.
Humans interface with electronic devices in a variety of applications, and there is a constant need for a more natural, easy-to-use, and versatile interface device. One of those applications includes interacting directly with computer-generated environments. Interface devices are used extensively with computer systems in the implementation of computer-controlled games, simulations, and other applications very popular with the mass market of home consumers. In a typical implementation, a computer system such as a personal computer, home video game console, portable computer, etc., displays a graphical environment to a user on a display device. Users can interact with the displayed environment by inputting commands or data from the interface device. Popular interface devices include joysticks, xe2x80x9cjoypadxe2x80x9d or xe2x80x9cgamepadxe2x80x9d button controllers, mice, trackballs, styluses, tablets, steering wheels, pressure spheres, foot or hand pedals, or the like, that are connected to the computer system controlling the displayed environment. The computer updates the environment in response to input signals from the interface device based on the user""s manipulation of a moved manipulandum such as a joystick handle, joypad, or mouse. The computer provides visual feedback to the user using the display screen.
In some interface devices, haptic (e.g., tactile and/or kinesthetic) feedback is also provided to the user, more generally known as xe2x80x9cforce feedbackxe2x80x9d herein. These types of interface devices can provide physical sensations to the user manipulating the physical object of the interface device. Typically, motors or other actuators of the interface device are coupled to the manipulandum and are connected to the controlling computer system. The computer system receives sensor signals from the interface device and sends appropriate force feedback control signals to the actuators in conjunction with host events. The actuators then provide forces on the manipulandum. The computer system can thus convey physical sensations to the user in conjunction with other visual and auditory feedback as the user is contacting the manipulandum. Commercially available force feedback devices include the ForceFX joystick from CH Products, Inc., the Wingman Force joystick and Wingman Formula Force steering wheel from Logitech, Inc., and the Sidewinder Force Feedback Pro joystick from Microsoft Corporation.
One problem occurring in commercially-available implementations of force feedback devices is that the devices are very bulky. A large base or support is typically required to house a large mechanism and/or large actuators. These features make it difficult to integrate compelling force feedback into a smaller interface device such as a handheld gamepad or joystick. The mechanisms provided in both regular and force feedback interface devices are typically expensive, complex mechanisms which in turn cause the cost of the interface devices to be expensive. Handheld interface devices are desired to be low cost items, making it difficult to incorporate accurate position sensing and/or force feedback functionality into these devices. Yet, these controllers are preferred by manufacturers as low-cost input devices for many types of systems, especially home video game consoles, and are also preferred by many consumers.
The present invention provides a flexure mechanism for an interface device that interfaces a user with a computer system. The flexure mechanism provides a low cost, easily manufactured mechanism that is stable and accurate.
More particularly, in one aspect of the present invention, an interface device is manipulated by a user and provides input signals to a host computer. The device includes a manipulandum physically contacted by the user and moveable in at least two rotary degrees of freedom. A five-bar closed-loop mechanism is coupled to the manipulandum to provide the two rotary degrees of freedom. The mechanism includes four members forming a unitary piece coupled to a ground, where the members are coupled to each other by flexible couplings allowing rotation of the members. A sensor, such as a rotary optical encoder or analog potentiometer, is coupled to the mechanism and senses a position of the manipulandum in at least one of the degrees of freedom and outputs a sensor signal, where a representation of the sensor signal is provided to the host computer. Preferably, each of the flexible couplings bends about only one rotational axis and may not twist.
The mechanism preferably includes two extension members and two central members flexibly coupled each other, where the manipulandum is coupled to one of the central members. In one embodiment, at least one actuator is coupled to the mechanism to output a force to the manipulandum in one or more of the degrees of freedom. In the preferred embodiments, the manipulandum is a joystick handle or at least a portion of a sphere, the device is in the form of a handheld gamepad or similar controller, and the computer is a home video console system or personal computer.
Preferably, the two degrees of freedom are provided about two base axes of rotation and the central members rotate about two floating axes of rotation, where flexible couplings between the extension members and the central members are substantially aligned with the floating axes of rotation. The central members can extend out of a plane formed by the axes of rotation. The flexible coupling between the central members can be substantially aligned with a normal axis extending approximately perpendicularly from a plane formed by the base axes when the central members are in an origin position.
The flexible couplings are preferably relatively thin in the dimension allowing flex and relatively thick in the dimensions in which the coupled members are to be rigid with respect to each other, where the flexible couplings allow bending and no twisting. At least two of the flexible couplings can be oriented such that when force is applied to the central members by the user contacting the manipulandum, a pulling tension is applied to the flexible couplings and their stability under the load is maintained.
In one preferred embodiment, the unitary piece of members includes a ground member coupled to the ground, where the first and second extension members are coupled to the ground member by flexible couplings. This embodiment provides flexible couplings for all the joints of the mechanism. These flexible couplings between the ground member and extension members are preferably substantially aligned with the base axes of rotation. The grounded member includes first and second sides arranged substantially perpendicular to each other in a single plane, and a first end of each extension member is coupled to the ground member at each side by the flexible couplings.
In a similar embodiment, an interface device manipulated by a user and providing input signals to a host computer includes a manipulandum and a mechanism coupled to the manipulandum that provides at least two rotary degrees of freedom about two axes of rotation. The mechanism is a closed loop five-bar linkage including five members, one of the five members being a ground, where at least two flexure couplings are provided to couple at least some of the five members to each other to allow the flexibly coupled members to bend with respect to each other. At least one sensor and actuators are provided to sense motion of and output forces to the manipulandum. The flexure couplings are preferably provided between a first extension member and a first central member and between a second extension member and a second central member; additional flexure couplings can be provided between first and second central members and between ground and the extension members. The flexure couplings are preferably aligned with and bend about only the axes of rotation and do not allow twist.
The present invention provides a compact, accurate, and stable mechanism for use in interface devices. The flexure mechanism is easily manufactured and requires minimal assembly, thereby greatly reducing the cost in producing both standard non-force-feedback interface devices as well as force feedback interface devices. The stiffness and accuracy of the mechanism allows precise sensing of motion as well as realistic and compelling conveyance of force sensations to a user of the device. The low cost and compactness of the mechanism allows easy integration into handheld interface devices.